Presence of subpleural pulmonary interstitial emphysema as an indication of single or multiple alveolar ruptures on CT in patients with spontaneous pneumomediastinum.

BackgroundThere are no previous reports regarding the computed tomography (CT) findings of subpleural pulmonary interstitial emphysema (PIE) in patients with spontaneous pneumomediastinum.PurposeTo evaluate CT findings of subpleural PIE that may indicate a direct site of terminal alveolar rupture.Material and MethodsWe retrospectively evaluated chest CT and the medical records of 34 patients with spontaneous pneumomediastinum. Subpleural PIE was defined as the presence of an interstitial air collection in the subpleural portion of the lungs excluding the bronchovascular bundle.ResultsSubpleural PIE on CT was identified in six of 34 patients (17.6%) with spontaneous pneumomediastinum. In four of these (66.7%), subpleural PIE was present in multiple lobes suggesting multiple simultaneous ruptures of terminal alveoli. The shape of subpleural PIE was elongated linear (4/6), branching and linear (1/6), and elliptical (1/6).ConclusionThe presence of subpleural PIE on CT suggests an origin of pneumomediastinal a...